cs 141 introduction to computer science and structured programming
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CS 141 Introduction to Computer Science and Structured Programming. Dr. Randy L. Ribler Lynchburg College. First Reading Assignment. Read Bronson Chapter 1. Today’s Topics. Studying computer science Careers in computer science CS141, and where it fits in - PowerPoint PPT PresentationTRANSCRIPT
CS 141Introduction to Computer Scienceand Structured Programming
Dr. Randy L. Ribler
Lynchburg College
First Reading Assignment
Read Bronson Chapter 1
Today’s Topics
Studying computer science Careers in computer science CS141, and where it fits in Hints on how to succeed in this course Compilers and Computer Languages
What is Computer Science?
Computer science is the study of computers and computer software.
It is really more like an engineering discipline than it is like a science.
Computer science is a very new field of study, yet it already has scores of subfields
A Sampling of Subfields in Computer Science
Artificial Intelligence (AI) Software Engineering Human-Computer Interaction (HCI) Parallel Processing Computer Graphics Computer Aided Design (CAD) Compiler Development/Tools Robotics
Simulation Performance Analysis Operating Systems Design Speech/Natural Language Recognition Database Design Theory of computation Virtual Reality (VR) Computer Architecture Web-based Technologies and many, many more.
What do these subfields have in common? Programming is central to almost every
one of these subfields.
Good things about Computer Science
You might really enjoy it! It is a very dynamic field
– but the “basics” tend to stay the same It is an applied “science.”
– You should be able to apply virtually everything you learn.
It can provide a very good career It can support work in virtually every
other field
Programming can be a very creative process. Programmers are writers and
engineers. There are many, many ways to
accomplish the same task. Computer science is very new. There
are a lot of opportunities to be innovative.
You can build new products without investing a lot of cash.
What do CS majors do when they graduate? Most are hired to develop software (program)
– Productivity Programs
– Operating Systems
– WEB Applications (e-commerce)
– Computer Graphics
– Artificial Intelligence
– Medical Software (CT Scan, MRI)
– Aerospace Applications
– Computation Biology
– Research
– Embedded Systems
– Military Applications
– Business Applications
– Educational Software
– Games
– Movies/Entertainment
What do CS majors do when they graduate?
Some work as network and system administrators Some go to graduate school Some get research jobs Some teach Some start their own companies
The Best Jobs in America
http://money.cnn.com/magazines/moneymag/bestjobs/2010/
Why is CS141 important?
It provides the basic tool set required in virtually every other CS class.
With CS141 and CS142, you can probably get a job as a programmer.
Without at least CS241 and CS242 (or equivalent) you probably shouldn’t be allowed to get a job as a programmer
Why do many students have trouble in CS141?
It’s probably not how the course is taught.– Every college with a CS program has a
course similar to CS141. – They all have relatively high numbers of
students who have difficulties They underestimate the amount of time they
need to devote to it. They get behind -- and because each concept
builds on the others, it is hard to catch up. They miss classes
How to Succeed in CS141 Spend time working on the programs Don’t miss any classes Read the textbook as assigned Come to office hours Ask questions in class Stay with the class (Don’t get behind). Start programs as soon as they’re assigned Expect to encounter problems Don’t get frustrated. If you keep trying, you’ll
get it. Understand that the programs are good
teachers -- learn from each mistake. Try to understand everything completly
Learning to program is like learning to play tennis. At first, you need to master fundamentals. It will get to be much more fun as you become better
at it. You need to practice. You can’t do all the practicing
the night before the match. It might be frustrating at first, but you will be rewarded
if you persevere. You can’t really judge how much you like it until you
get to a certain level of competency. Most people can do it if they dedicate enough time to
it.
A more gentle introduction is available CS131 (3 credits) MWF 10:00-10:50
– Visual Basic– Recommended for those who have never
done any programming before. CS141 is much more demanding
What do computers do? They do very, very, simple things
– basic arithmetic on values in memory– Input/Output– Comparison and Conditional Execution
• if-statements
They do it very, very, fast and very, very reliably.
Programmers build systems to do complicated things using these simple basic capabilities.
Think of a recipe.
We can use instructions that provide different levels of detail.– High Level
• Make an apple pie
– Lower Level• Slice 4 apples into one inch squares...
– Even Lower Level– Pick up a knife, place the knife on the
apple, apply pressure, …
Cooks use a standard set of instructions Poach Blend Whip Fry Filet
Recipes consist of a known set of instructions.
Cooks translate these higher-level actions.
Computer Languages
A computer language defines the set of instructions that the programmer can use.
Programs are collections of these instructions.
Computer Hardware Executes Low-level Instructions
Programmers typically want to write programs using higher level instructions.
Different computer manufactures provide different low-level instructions.
High-level Languages High-level languages allow
programmers to use a more expressive set of instructions.
A compiler translates the high-level instructions the programmer writes to the low-level instruction set the computer understands.
Compilers allow programs to be portable, because the instructions are not tied to an particular instruction set.
Compilers Translate High-level instructions to a particular machine’s (native) instruction set.
Program written in High-levelLanguage
Compiler
Program usingnative
instruction set
The program the programmer writes is called source code.
The program the compiler generates is called object code.
Compilers Translate High-level instructions to a particular machine’s (native) instruction set.
Program written in High-levelLanguage
MicrosoftCompiler
Program using Intel
instruction set
AppleCompiler
Program using Motorola
instruction set
Source code Object code
Programming Languages FORTRAN - Scientific/Engineering (1957) COBOL - business oriented language (1959) C - applications and systems, dominated much of the
eighties and early nineties. (K&R published 1978) C++ - applications and systems, dominated much of the
late nineties. (1980-1985) Java - applications and network/web-based applications,
rapidly gaining popularity. (1995) Lisp and Prolog - Languages for AI (1959, 1970) Pascal - language used to teach programming (1971) Ada - language used in military applications (1983) Basic - language used to teach programming (1965)